Block Polymer Membrane Adsorbers Chemically-Tailored for Selenium Sorption

Abstract: Traditionally, the targeted capture of analytes relies on packed beds for high-recovery and high-capacity sorption. Membrane adsorbers provide an alternative technological pathway that replaces microporous resins with high-flux membranes. However, these devices are stymied by low sorption capacities, complex processing methodologies, and have limited tunability. Here, we demonstrate the use of the self-assembly and non-solvent induced phase separation (SNIPS) technique to generate nanoporous thin films with tunable pore wall chemistries; in this way, chemically-selective membranes can be generated in a straightforward manner. Specifically, the A-B-C triblock polymer polyisoprene-b-polystyrene-b-poly(N,N-dimethylacrylamide) (PI-PS-PDMA) is processed from solution to yield a membrane with a pore density of ~10¹³ pores m^-2. The PDMA moiety that lines the pore walls is converted, quantitatively, to thiol group chemical functionalities in the solid state using facile reaction conditions. These thiol-functionalized membranes act as high capacity, high flux adsorbers for the removal of selenium salts from an aqueous solution. This scalable system demonstrates a platform for high-flux chemically-selective purification for use in next-generation industrial water treatment and reuse applications.